The field of the invention relates generally to cooling of structures, and more specifically, to methods and apparatus for a micro-truss based structural insulation layer.
There are at least two known types of cross-flow heat exchangers: a plate-and-fin heat exchanger and a microtruss heat exchanger. The plate-and-fin heat exchangers include metal plates having fins extending between adjacent plates. Hot and cold fluids flow past the fins between the plates, losing and gaining heat by convection, and the fins conduct heat to or from the plates. If the fluid has particulates entrained in its flow, the particulates may become lodged between the fins and clog the heat exchanger. Further, the plate-and-fin heat exchange relies on transferred heat to and from the plates. The microtruss heat exchanger includes struts that intersect at nodes. A fluid flows past the struts and nodes. When the struts are solid, heat is transferred between the fluid and the struts. When the struts are hollow, a second fluid flows through the struts, and heat is transferred between the struts and the second fluid to heat or cool the first fluid. As such, one purpose of a heat exchanger is to exchange heat between two fluids. However, another purpose may be to cool, heat, and/or insulate a structure to which the heat exchanger is mounted.
Known microtruss heat exchangers include four struts (4-fold) or more struts intersecting at each node, providing more strut surfaces for the first fluid to interact with. Further, the 4-fold truss structure may allow the heat exchanger to be load bearing if a component surrounding the heat exchanger fails. However, the density of struts in 4-fold microtruss structure is so high that upstream struts may reduce the first fluid from flowing past the leading edges of the downstream struts, and therefore reduce their heat transfer the operational efficiency of the heat exchanger. For example, a leading edge of a downstream strut is covered by a trailing edge of an upstream strut, causing the downstream strut to have less exposed area for heat transfer. As such, heat transfer at the downstream struts is reduced as compared to heat transfer at the upstream struts, which are not blocked from interacting with a cooling flow.